The climate is getting warmer, and terrestrial ecosystems are responding. Species move up mountain slopes to remain in the temperature regimes they prefer (if there is a mountain slope to move up!). What is happening in the oceans? The warming climate is affecting ocean temperatures too, thought the oceans have vast thermal mass, so changes might be expected to be occurring more slowly than on land.

ADVERTISEMENT

Oceans cover 71 percent of the Earth's surface, yet our knowledge of the impact of climate change on marine habitats is a mere drop in the proverbial ocean compared to terrestrial systems. An international team of scientists set out to change that by conducting a global meta-analysis of climate change impacts on marine systems.

Counter to previous thinking, marine species are shifting their geographic distribution toward the poles and doing so much faster than their land-based counterparts. The findings were published in Nature Climate Change.The three-year study, conducted by a working group of UC Santa Barbara's National Center for Ecological Analysis and Synthesis (NCEAS) and funded by the National Science Foundation, shows that warming oceans are causing marine species to change breeding, feeding, and migration timing as well as shift where they live. Widespread systemic shifts in measures such as distribution of species and phenology — the timing of nature's calendar — are on a scale comparable to or greater than those observed on land.

"The leading edge or front-line of marine species distributions is moving toward the poles at an average of 72 kilometers (about 45 miles) per decade — considerably faster than terrestrial species, which are moving poleward at an average of 6 kilometers (about 4 miles) per decade," said lead author Elvira Poloczanska, a research scientist with Australia's national science agency, the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Marine and Atmospheric Research in Brisbane. "And this is occurring even though sea surface temperatures are warming three times slower than land temperatures."

The report, which involved scientists from 17 institutions, including NCEAS associates Carrie Kappel and Ben Halpern and former NCEAS postdoctoral associates Mary O'Connor, Lauren Buckley, and Camille Parmesan, forms part of the Fifth Assessment Report of the United Nations Intergovernmental Panel for Climate Change (IPCC). The Geneva-based IPCC assesses scientific, technical, and socioeconomic information concerning climate change, its potential effects, and options for adaptation and mitigation.

"The effects of climate change on marine species have not been a major focus of past IPCC reports because no one had done the work to pull together all the disparate observations from around the world," said Kappel. "This study provides a solid basis for including marine impacts in the latest global accounting of how climate change is affecting our world."

Unlike previous climate change assessments, which relied heavily on terrestrial data to estimate marine impacts, the NCEAS working group scientists gathered from seven countries to assemble a large marine-only database of 1,735 changes in marine life from the global peer-reviewed literature. The biological changes were documented from time series, with an average length of 40 years of observation.